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The drug, Keytruda (pembrolizumab), was tested on more than 600 patients who had melanoma that had spread throughout their bodies. Because so many of the patients in the early testing showed significant long-lasting responses, the study was continued and the FDA granted the drug “breakthrough therapy” status, allowing it to be fast-tracked for approval.

The largest Phase 1 study in the history of oncology, the research was conducted at UCLA and 11 other sites in the U.S., Europe and Australia.

Keytruda, formerly known as MK-3475, is an antibody that targets a protein called PD-1 that is expressed by immune cells. The protein puts the immune system’s brakes on, keeping its T cells from recognizing and attacking cancer cells, said Dr. Antoni Ribas, the study’s principal investigator and a professor of medicine in the division of hematology-oncology at the David Geffen School of Medicine at UCLA.

For many years, when using immunotherapy to fight cancer, doctors’ strategy has been to bolster the immune system so it could kill the cancer cells. But the approach had limited success because PD-1 prevented the immune system from becoming active enough to attack the cancer.

Keytruda, in effect, cuts the brake lines, freeing up the immune system to attack the cancer.

“This drug is a game changer, a very significant advance in the treatment of melanoma,” said Ribas, who also is a researcher at UCLA’s Jonsson Comprehensive Cancer Center. “For patients who have not responded to prior therapies, this drug now provides a very real chance to shrink their tumors and the hope of a lasting response to treatment.”

Judith Gasson, senior associate dean for research at the David Geffen School of Medicine at UCLA and director of the Jonsson Cancer Center, said researchers have long hoped to develop an effective and lasting immunotherapy to fight cancer.

“We have long believed that harnessing the power of our own immune systems would dramatically alter cancer treatment,” she said. “Based upon work conducted over the past two decades, we are beginning to see the clinical benefits of this research in some of the most challenging cancers.”

Generally, about 1 in 10 patients responded to previous immunotherapy drugs. Some of those who responded, however, exhibited long-lived benefits, which sustained scientists’ interest in the method as an effective mechanism to fight cancer.

The response and duration rates for Keytruda were much greater than for previous drugs, Ribas said. In the new study, 72 percent of patients responded to the drug, meaning that their tumors shrank to some degree. Overall, 34 percent of patients showed an objective response, meaning that their tumors shrank by more than 30 percent, and did not re-grow.

Ribas said Keytruda has the potential to be used to treat other cancers that the immune system can recognize, including cancers of the lung, bladder, head and neck.

Survivors’ stories Kathy Thomas, 59, of Torrance, California, was diagnosed in September 2011 with melanoma that had spread to her liver and was invading her left breast. She underwent several therapies that did not work, and she was weakening fast.

“I lost weight. I threw up nearly every day,” Thomas said. “My hair was thinning. I just had no strength at all. I was so sick I had to use a wheelchair.”

Thomas met with Ribas in 2012 but was skeptical about enrolling in a trial to test an experimental therapy. She soon overcame her hesitation.

Since enrolling in the study, Thomas’ tumors have shrunk. She regained her strength and her appetite. She’s out of her wheelchair and walking normally again. She said she has experienced no side effects from the therapy, and she travels monthly to San Francisco to visit her grandson.

Tom Stutz, 74, of Sherman Oaks, California, was diagnosed in June 2011 with melanoma that had spread to his lung, liver and other parts of his body. He didn’t see how he could survive, but he decided to enroll in the clinical trial of Keytruda anyway.

“I wasn’t eating. I was on oxygen. I couldn’t walk,” he said. “When I went into the hospital at the end of May [2012], I didn’t think I was coming out.”

Gradually, though, Stutz started feeling better. Today, he’s no longer on oxygen and walks several miles every day.

“It’s the little things that make me happy now,” Stutz said. “I’m very appreciative that I get to get up in the morning, go into my backyard and see my garden. I’m able to be with my children and grandchildren, go on vacations with them. I was close to the end of the road, as far as you can get to the edge of the cliff, and I was pulled back by this treatment.”

Melanoma incidence rates have been increasing for at least 30 years. An estimated 76,100 new cases of melanoma will be diagnosed in the U.S. in 2014, and nearly 10,000 Americans will die from the disease this year. While melanoma accounts for less than 2 percent of all skin cancer cases, it is responsible for the vast majority of skin cancer deaths, according to the American Cancer Society.

The multi-institutional group, led by scientists at Cancer and Blood Diseases Institute (CBDI) at Cincinnati Children’s Hospital Medical Center, publish their results in the journal’s online edition on Aug. 24. The researchers suggest their laboratory findings in mouse models of the disease could lead to a more targeted and effective molecular therapy that would also reduce the harmful side effects of current treatments, which include chemotherapy, radiation or surgery.

“Although current treatments improve survival rates, patients suffer severe side effects and relapse tumors carry mutations that resist treatment,” said lead investigator Q. Richard Lu, PhD, scientific director of the Brain Tumor Center, part of the CBDI at Cincinnati Children’s. “This underscores an urgent need for alternative targeted therapies, and we have identified a potent tumor suppressor that could help a subset of patients with an aggressive form of medulloblastoma.”

Using genetically-engineered mice to model human medulloblastoma, the authors identified a gene called GNAS that encodes a protein called Gsa. Gsa kicks off a signaling cascade that researchers found suppresses the initiation of an aggressive form of medulloblastoma driven by a protein called Sonic hedgehog — considered one of the most important molecules in tissue formation and development.

The scientists used an anti-depressant medication called Rolipram — approved for behavioral therapy for use in Europe and Japan — to treat mice that were engineered not to express the GNAS gene. Lack of GNAS allowed aggressive formation of medulloblastoma tumors in neural progenitor cells of the GNAS mutant mice.

Rolipram treatment in the mice elevated levels of a molecule called cAMP, which restored the GNAS-Gsa pathway’s tumor suppression function. This caused the tumors to shrink and subside. The study also suggests that elevating cAMP levels in cells enhances the potency of Sonic hedgehog inhibitors, currently being tested in clinical trials to fight tumor growth.

The scientists stressed that a significant amount of additional research is needed before their findings could become directly relevant to clinical treatment. The authors also caution that the effect of raising cAMP levels may depend on the type of cancer, and that laboratory results in mice do not always translate uniformly to humans.

The markers are variations in the inherited DNA code at particular locations along chromosomes. Several of these variations in the DNA code were identified that influence an individual’s risk for pancreatic cancer.

The discovery of these markers — along with four that were previously identified is important for several reasons, said Brian Wolpin, MD, MPH, first author of the report published online by Nature Genetics. One is that further study of these DNA variants may help explain on the molecular level why some people are more or less susceptible to pancreatic cancer than the average person. A second is the potential to identify people at increased risk who then might be candidates to undergo MRI or ultrasound scanning to look for early, treatable pancreatic tumors.

“Currently there is no population screening program for pancreatic cancer, which in 80 percent of cases is discovered when it’s too late to allow curative surgery — the cancer has already spread,” said Wolpin.

The only healthy individuals currently screened for pancreatic cancer are members of high risk families due to multiple family members with pancreatic cancer. “But the field has been struggling to find factors that can identify people at highest risk in the general population, when a strong family history is not present,” Wolpin said.

The study findings represent analyses of DNA from 7,683 patients with pancreatic cancer and 14,397 control patients without this cancer, all of European descent, from the United States, Europe, Canada, and Australia. The scientists used sequencing technology to examine more than 700,000 sites of the genome known to have single nucleotide polymorphisms (SNPs) — differing versions of a single letter of DNA code. These variations can alter the expression of a gene or the content of its message, and the researchers looked for variants that were associated with the risk of having pancreatic cancer. Research of this type is called a genome-wide association study, or GWAS.

Wolpin said the results confirmed the presence of four risk-associated SNPs that had been identified in a previous, smaller GWAS study. In addition, five new risk markers were discovered and a sixth that was of borderline statistical significance.

The risks linked to each SNP or marker were largely independent and additive, so that they may have utility in future attempts to identify individuals in the general population at higher risk for pancreatic cancer. The average lifetime risk of pancreatic cancer is 1.5 percent.

The long-term goal is to create a “risk stratification tool” that could be used in primary care practice to identify individuals who should undergo screening for pancreatic cancer with tests such as ultrasound or MRI.

The report includes authors from around the world, and includes several senior authors, one of whom is Charles Fuchs, MD, MPH, of Dana-Farber.

The project, known as PanScan III, was funded by numerous sources, including the National Cancer Institute of the National Institutes of Health under contract number HHSN261200800001E and the Lustgarten Foundation.